Variable air condenser



May 15, 1934. L. A. GEBHARD VARIABLE AIR coNDENsER Filed Dec. 24 1950 2Sheets-Sheet l mw, w ma W ma? w WA w -MY MB w May 15, 1934. L. A.GEBHARD VRIABLE AIR CONDENSER Filed Dec. 24, 1930 2 Sheets-Sheet 2 1IIIIIIIIIIJ`VIII'IIIIl/I W O f f z 3 z W w z 7 8 .w a W w ,a z JF: AW Oma w Q w AM O r z (WI O Z k f fa f ,7M fa ATTORNEY Patented May 15, 1934UNITED STATES I 1,958,4z4 PATENT OFFICE Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. G. 757) My invention relates broadly tohigh frequency signaling systems and more particularly to an improvedconstruction of variable air condenser for high frequency signalingsystems.

In a high frequency transmitter covering a wide frequency band, it isdesirable to have the frequency controlled by variable condensers whichhave a large ratio of minimum to maximum capacity. This condition isrequired in order that the widest possible frequency band may becovered. In high power circuits the push-pull tube arrangement isgenerally used. This requires symmetry of all parts of the circuit andtherefore of the variable condensers used. It is also desirable wherethe condenser is used in circuits of very high frequency to have thecapacity between high potential points of the condenser and ground ofminimum value. It is desirable, therefore, to arrange the condenser sothat the controls, etc., which have fairly large capacity will be atsubstantially ground potential.

My invention has for its object the construction of a high frequencycondenser for transmitters utilizing a push-pull power amplifier systemby which symmetry may be maintained throughout the adjustment of thecondenser over a wide frequency band where the condenser has a largeratio of maximum to minimum capacity.

Another object of my invention is to provide means for supporting amultiplicity of fixed plates in a symmetrical condenser system withrespect to a set of adjustable plates with a single 85 control foradjusting the capacity of different portions of the condenser systemsimultaneously, the arrangement of plates being such that a minimumcapacity exists between lthe points of high potential in the condenserand the ground.

Other and further objects of my invention reside in the construction ofa symmetrical condenser system as set forth more fully in thespecification hereinafter following by reference to the accompanyingdrawings, wherein:

Figure 1 is a side elevation of the condenser system of my invention;Fig. 2 is a cross-sectional view through the condenser on line 2--2 ofFig. 1; Fig. 3 is a Vertical sectional view of the condenser on line 3-3of Fig. 1; and Fig. 4 is a Vertical sectional view through the condenseron line 4-4 of Fig. 1.

The high potential plates of the condenser are arranged in two banks 1and 2 with plates in the respective banks set edge to edge and parallel.Into the space between these stationary plates the movable group plates3 are introduced. Groups 1 and 2 are supported by means of spacers 4from insulating member 5. Movable group of plates 3 is supported fromthreaded rods 6 and 7 by means of screw threaded members 8.

Screw threaded members 8 are attached to spacers 9 which serve to holdthe plates of the group 3 apart. Threaded rods 6 and 7 are supported inbearings 10 and 11 which are in turn mounted on insulating member 5. Theupper ends of the threaded rods 6 and 7 are supported in bearings 12 and13 which are in turn supported from insulating member 14. Bevel gears 15and 16 provide simultaneous control by crank 17 through fiexiblecouplings 18 and 18a of the two threaded rods 6 and 7. Bevel gears 19and counter 20 which is visible from the front panel 21 of thetransmitter permit resetting the condenser to any particular point.Insulating members 5 and 14 are held together by means of supports 22 soas to form a rigid frame work for the condenser which is supported fromthe frame work of the set as shown at 23.

The sets of high potential plates 1 and 2 are illustrated as three innumber in the arrangement shown in the drawings, however, additionalplates may be employed. The spacer members 4 serve to maintain theplates in a Vertical plane. The sets of stationary plates 1 and 2 havethe individual plate members thereof electrically interconnected by therod or bolt members 25 which pass through the spacer members 4 and arebonded to the plates. The members 4 are rigidlyv secured to thelaterally extending insulating frame member 5 by screw members 4a. Thecentral plate (or plates) is bonded to the interconnecting members 25forming an extension of the capacity areas established by the outerplates of the sets of plates 1 and 2.

The spacers 9 which maintain the spacial relat-ion of the adjustableplates 3 have bolt meinbers 26 extending therethrough which, with thespacers 9, serve to electrically bond and mechanically embrace theadjustable plates as a unitv The screw threaded lugs 8 which are engagedby the screws 6 and 7 are rigidly connected to the spacer members 9 byscrew members 27 which pass into the spacers. The movable plates 3 areadjusted vertically with respect to the sets of stationary plates 1 and2 to a position which is symmetrical with respect to each portion of theamplifier circuit with which the high potential condenser is designed tocooperate. The control and parts connected thereto which have a fairlylarge capacity, are substantially at ground potential. A large ratio ofmaximum to minimum capacity is obtainable by reason of the wideVariation in the spacing relation of the condenser plates which it ispossible to obtain.

While I have described the high potential condenser of my invention incertain preferred embodiments, I desire that it be understood thatmodifications may be made and that no limitations upon my invention areintended other than are imposed by the scope of the appended claims.

The invention herein described may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. A variable air condenser comprising an insulated frame structure,independent sets of condenser plates erected in Vertical 'planes uponsaid insulated frame structure, a pair of rotatable screws disposed onopposite sides of said vertically disposed condenser plates, a set ofad- V;ustable plates, a pair of members respectively engagng saidrotatable screws and respectively attached to each of said adjustableplates at points thereof substantially spaced apart, and means forselecting the position of said adjustable plates with respect to saidsets of condenser plates.

2. A variable air condenser comprising a laterally extending insulatedframe structure, duplicatesets of condenser plates disposed in Verticalplanes, means extending from said insulating frame structure andsecuredto the lower extremitiesof saidy condenser plates for erecting andmaintaining said plates in Vertical planes, a pair of rotatable screwsdisposed adjlacent the remote edges of each of said sets of plates, aset of adjustable plates, means including a plurality of threaded lugssupportingly attached to said adjustable plates for adjustment thereofin cooperation with said screws and means for actuating said screws, forshifting the position of said `adjustable plates with respect to saidfirst mentioned sets of condenser plates for changing Vthe electricalcapacity. with respect to said duplicate sets of lcondenser plates inequal amounts.

3. Ina'variable air condenser, a frame structure comprising a pair oflaterally extending frame members of insulating material, a pair ofrotatable screwithreaded shafts extending vertically between saidllaterally extending frame members,independent sets of condenser plateserected vertically Aupon one of said frame members and disposed betweensaid rotatable shafts, a set o f adjustable plates, screw threadedmembers connected with the endsV of said adjustable .plates at pointsthereof spaced substantially apart and engaging said rotatable screwthreaded members, :and means for rotatably driving said screw threadedshaft members for variably interleaving said adjustable plates with saidindependent sets of Vvertically' erected plates.

` 4. In a variable air condenser, Va Vframe structure comprising a'pairof insulation members, a pairof screw threaded Vrotatable shaftsextending between Vand journalled with respect to said pair ofinsulation members, a plurality of threaded lugs engaging said rotatablescrew threaded shafts, -a set of adjustable condenser plates,

mounted on said threaded lugs independent sets' Vof fixed condenserplates supported by one of said of condenser plates, a set ofadjustablecondenser plates extending between said shaft members,

screw threaded members attached -to each of said adjustable condenserplates at, at least, two spaced pointson opposite edges thereof andengaging said rotatable shaft members for maintaining said set ofadjustable plates in a balanced 'adjustable condenser plates at pointssubstantially spacedV apart and engaging the screw threads on saidrotatable shafts, and means for imparting equal rotatable movements Vtosaidv shafts for shifting the position of said set of adjustable platesrectilinearly and in proportionate relation to Veach said independentset of condenser plates.

77. A'Variableair condenser comprisng incom-iV bination, a framestructure, a plurality of independent sets of stator plates, the setsbeing 'insulated from one another and from said frame structure .bywhich they are supported, a set of adjustable plates adapted Vto beinterleaved'with said stator plates, and means including a plurality ofscrew driven lugs attached to said adjustable plates for Vadjustablypositioning the same whereby the capacitative relation ofv saidadjustable plates to each set of stator plates is proportionatelyvaried. i

8. A device in accordance with'claim 7, in

which said adjustable plates are movable in a' rectilinear direction andcorresponding'plates of the stator sets are arranged to be inteleavedby' each single adjustableplate.

9. In a variable air condenser, a frame structure comprising laterallyetending insulation members, a plurality of sets of stator plate memberssupported by one of said insulation`members,

means electrically andimechanically bonding together the stator platemembers of each said set as an independent capacity unit, a set ofadjustable plates electrostatically common to the several sets of statorplate members, 'and means for shifting the position-of said adjustableplatesV rectilinearly in respect to said stator plate'members forvarying the capacity relation to each set` thereof proportionately.

' 10. In a variable air condenser, a frame structure comprisinglaterally extendingl insulation members and transversely extendingplatesupporting members, independent sets of stator plates held by saidtransversely extending members, the plates of each set beingelectrically bonded together thereby, a pair of rotatable screw 'ithreaded shafts carried by said laterally extending insulation members,a plurality of screw threaded lugs engaging said shafts, and a set ofadjustable condenser plates supported by said screw threaded lugs andadapted to be variably interleaved With said independent sets of statorplate members, the adjustn'ient thereof lbein provided by rotativemovement of said Vscrew

